| Objective: Ovarian cancer(OC) is one of the most common femalereproductive tract malignant tumors, and the incidence up to the sixth place ofall female cancers. Epithelial ovarian cancer (EOC) is the most commonovarian cancer which comes from ovarian epithelial layer, and lead to120,000patients died in the cancer per year, its mortality rank first in all ofgynecological tumors. The high mortality of epithelial ovarian cancer ismainly dued to most patients absence of specific symptoms at early stage,more than70%preliminary patients with ovarian cancer are diagnosed atadvanced stage, and had lost the opportunity of surgical therapy. If ovariancancers were found at early stage and adopted active therapy, the5-yearsurvival rate would be greater than90%. The mainly treatment of ovariancancers is cytoreductive surgery combine chemotherapy. Although thepersistent development of diagnosis and chemotherapy technology, the5-yearsurvival rate of ovarian cancers is only30%, and most patients could relapseand become drug resistance. So, what is the root of the ovarian cancer relapseand drug resistance, what kind of cytokines can inhibit or promote theoccurrence and development of tumor? Most scholars keen on this view, butso far still no breakthrough progress.MicroRNAs (miRNAs) are kinds of endogenous noncoding nucleotidesingle-stranded RNA molecule which length rang18-24, and exists in theorganism widely. miRNAs play important effects in the proliferation,differentiation, apoptosis of cells, and so as in ontogeny. The miRNAs doesn’tencode any protein, they regulate approximately30%of human genes throughthe ways of degradation or inhibition, negatively regulate the expression oftarget genes. A large number of studies have shown that the changes ofmiRNAs expression are closely related to the occurrence and development of human tumors, including the tumorigenesis, proliferation, apoptosis, invasion,metastasis and drug resistance, etc. The mutations, deletions, and abnormallevels of expression of miRNAs are the common characteristics of cancers.Inthe number of miRNAs,some miRNAs play effect as “inhibiting oncogene”and some as “tumor suppressor gene”. Which “tumor suppressor gene” ofmiRNAs can function the target genes, and reverse the development ofcancers. MicroRNA145(miR-145) is a subtype of the miRNAs familys.Research confirmed that miR-145is a tumor suppressor, it can inhibit thepluripotency of tumor stem cell and then affect the growth and metastasis oftumor cells.The reduction of expression level of miR-145could decrease theeffect toward the target genes and then promote the occurrence of tumor,therefore, The lack of miR-145expression is associated with the malignantbehavior of tumor cells and it is associated with the drug resistance of tumorclosely. It has been reported that miR-145is correlated with the drug resistantof lung cancer, but the correlation between miR-145and drug resistance ofovarian cancer hasn’t been reported.The purpose of this study lied in detect the correlation of miR-145anddrug resistance of ovarian cancer. We want to see if there are correlationbetween miR-145and drug resistance of ovarian cancer through detect thedifferent expression of miR-145in epithelial ovarian cancer cell,drug-resistant cell and transplantation tumor of nude mice.It providedexperimental basis for further experimental study that transfection ofmiR-145inhibited tumor resistant, then expecting that the miR-145willbecome a kind of tumor inhibitor and a new kind of anti-tumor therapy in thetreatment of malignant tumors.Methods：1Cell culture: ovarian serous papillary adenocarcinoma cell line SKOV3were maintained in RPMI-1640, containing10%fetal bovine serum (FBS) at37℃,5%CO2, humidified incubator culture.2Construction of transplantation tumor model:Non-drug-resistant humanovarian serous adenocarcinoma cell line SKOV3and cisplatin-resistant human epithelial ovarian cancer cell Line were conventionally cultured.we collectedcancer cell until the cells growing to80%-90%of bottle bottom.when thecells were sufficiently dispersed, counted and made single cell suspension at adensity of5×107/ml. The suspension (about1×107cells per nude in0.2mlsuspension) was inoculated at subcutaneous of the nude mouse’s dorsal nearhindlimb in sterile conditions.After10days of inoculation,choose thesuccessful model with transplanted tumor about5~8mm in diameter.It wasput in liquid nitrogen immediately to prepare for flowing RT-qPCR.3RT-PCR test:take the tumor tissues which were stored at-80℃andwithout reagents fixed, using RT-PCR technology to detect the expression ofmiRNA-145in the transplanted tumor and cancer cell.4The statistical method: SPSS17.0statistical software processing of theexperimental data. The Student t test was used to statistical analyze thedifferent expression of miR-145in epithelial ovarian cancer cell,drug-resistant cell and transplantation tumor of nude mice. Statisticalsignificance was set at P<0.05.Results：1The expresstion level of MiR-145in SKOV3/DDP cell was lower thanin SKOV3cell （0.45±0.07vs1.09±0.16P<0.05）, and there wasstatistically significant difference.2The expresstion level of MiR-145in SKOV3/DDP transplantationtumor was lower than in SKOV3transplantation tumor （0.41±0.06vs1.13±0.34P<0.05）, and there was statistically significant difference.3The expresstion level of MiR-145in SKOV3cells vitro was lower thanin SKOV3transplantation tumor(0.41±0.06vs1.13±0.34P<0.05）, and therewas statistically significant difference.Conclusion：1Either in cultured ovarian cancer cells in vivo or vitro, the expresstionlevel of miRNA-145in drug resistant ovarian cancer cells was lower thannon-drug resistant ovarian cancer cells. miR-145was related with the drugresistance of ovarian cancer, the reduction of expression level of miRNA-145 could decrease the effect toward the target genes and cause the drug resistanceof epithelial ovarian cancer.2The expresstion level of miRNA-145in SKOV3cells vitro was lowerthan in in SKOV3transplantation tumor, this was similar to the changesexpression of embryonic stem cells (ESCs) and differentiated cells. |
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